I do have P clips and some other mounting pieces that came with an EVO bike rack I put on my mountain bike. They have a rubber sleeve around the clamp so that seems safer for the paint then a metal bracket screwed in around the seat stays? I would think a nice hard resin plastic bracket would make more sense than a sharp steel or metal bracket.

thanks for the responses, all. I have no money invested in the rack so if I can't safely attach it to my nice steel Sakai 12 speed I'll move on. Not worth damaging the paint job, that's for sure.